1. Field of the Invention
The present invention relates to an early brake driving method of a disk system and a circuit thereof such as an Optical Disk Driver, Compact Disk Player, CD-ROM, CD-XA, CD-1 and the like, and more particularly to an early brake driving method of a disk system and a circuit thereof which can control a lens vibration early during a stoppage of a pickup to thereby cause an early tracking, so that a high access can be made possible.
2. Description of the Prior Art
Generally, because a large capacity of digital information are stored in a disk of a disk system, a fast pickup driving should be realized and a swift tracking should be realized as well.
However, when the pickup is moved and stopped as in a track seek, the pickup has a drawback in that it slips due to inertia or the lens on the pickup vibrates to thereby disable the tracking from realizing quickly.
FIG.1 is a drawing of a conventional brake driving circuit having the aforesaid drawback.
In FIG. 1, a lock signal generating unit 100 outputs lock signals when a Constant Linear Velocity CLV is realized, and when the CLV is not realized, outputs unlock signals.
A brake circuit 200 is carried into a brake mode to thereby perform the tracking when the lock signals are outputted from the lock signal generating unit 100, and when unlock signals are outputted, the brake circuit does not perform the tracking due to a release of the brake mode.
In other words, during a normal reproduction, because the CLV is realized, the brake circuit is changed into a brake mode for performance of the tracking, however when the pickup is moved to radiant directions as in the track seek, the CLV is not realized to thereby release the brake mode, so that the tracking is not conducted.
FIGS. 2a-2d are timing drawings for explaining operational states of FIG. 1.
First of all, when a feed motor driving signal is outputted ON in order to move the pickup to radiant directions of the disk as in FIG. 2a during the track seek, the lock signal generating unit 100 transmits the lock signals to unlock signals to thereby output the same after a predetermined time (around 16 ms) is passed as shown in FIG. 2b because the CLV has not been realized.
Henceforth, even though the feed motor driving signal (see FIG. 2a) is rendered off, the lock signal generating unit 100 keeps outputting unlock signals as illustrated in FIG. 2b, and outputs lock signals when the CLV is realized.
Meanwhile, when the feed motor driving signals are outputted ON as illustrated in FIG. 2a, the pickup and lens move as illustrated in FIG. 2d, and when the feed motor driving signals are turned off, the pickup and the lens are stopped.
However, the lens vibrates due to inertia for a predetermined period of time (.DELTA.T) even after the pickup is stopped within a shortest possible period of time T1, causing the tracking not to be realized.
In other words, because the brake circuit 200 comes to an unlock state, which implies that the same is under a release of the brake mode, the tracking is not realized, resulting in a problem that the tracking is not realized quickly during the track seek.
For example, in U.S. Pat. No. 4,942,567 entitled, "Disk Reproducing Method", a method is presented to reduce a track flow appearing due to a track jump or an external shock.
The U.S. Pat. No. 4,942,567 conducts conventional reproducing operations, and when the external shock is inflicted on, and when a first servo circuit is released of the lock state for a predetermined period of time, a second and a third servo circuit are rendered off to thereby reduce the track flow which can happen during a reproducing operation of the pickup.
Furthermore, a tracking actuator is always locked in the vicinity of a neutral point, resulting in a reduction of an amount of correction of the slider.
Even in the braking mode, the tracking servo circuit can quickly be locked.
However, because the aforesaid U.S. Pat. No. 4,942,567 can not either prevent the vibration of the lens from occurring during the track seek when the pickup is stopped, the problem still exists that a fast tracking can not be realized.
In other words, when the pickup stops at an objected place during the seek, the lens vibrates due to the inertia, causing a problem that an object track can not be accessed at a high speed.